Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ turbines in their design and operation. Some of these turbines include rotors (e.g., drum-style rotor, wheel/diaphragm-style rotor, etc.) employing a plurality of tangential dovetail blades. These blades (or “buckets”) are installed circumferentially about the rotor via an entry slot in the rotor body. Additionally, a plurality of stages (or rows) of blades may be present in any particular design.
In some styles of bucket design, integral covers or shrouds at the opposite end from the dovetail of the turbine buckets are intended to maintain contact from bucket to bucket in a row, to dampen vibratory stimuli and control natural frequencies during operation of the turbine. The integral covers of the turbine buckets are typically designed such that there is an initial pretwist or preloading of the turbine bucket covers and blades, in order to control these vibrational characteristics. The dovetail features and rotor interface must provide reaction to this rotational force.